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Corrosion
& Environmental Degradation |
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·
The
diagram shows an active/passive system under corrosion conditions with
three reduction reactions indicated.
·
For
the first condition, the corrosion parameters correspond to point A where
the reduction and oxidation curves cross. In this state the system is corroding
at the only allowed rate.
·
For
the second condition two stable corrosion states exist: B a normal corroding
condition and D a passivated state. C is unstable and not realizable in
steady state. |
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From:
M.G. Fontana, "Corrosion Engineering,"
Wiley
(1986) |
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·
The
system may jump between the states B and D causing several orders of magnitude
in the corrosion rate.
·
In
the third condition, there is only one intersection, E, between the reduction
and oxidation curves. In this state the material is passivated. |
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